U.S. patent application number 11/143996 was filed with the patent office on 2005-12-08 for optical disk recording/reproducing method, optical disk recording/reproducing apparatus and optical disk.
Invention is credited to Iwanaga, Toshiaki, Kashihara, Yutaka, Morishita, Naoki, Nakano, Masaki, Ogawa, Akihito, Ogawa, Masatsugu, Ookubo, Shuichi.
Application Number | 20050270939 11/143996 |
Document ID | / |
Family ID | 34939544 |
Filed Date | 2005-12-08 |
United States Patent
Application |
20050270939 |
Kind Code |
A1 |
Kashihara, Yutaka ; et
al. |
December 8, 2005 |
Optical disk recording/reproducing method, optical disk
recording/reproducing apparatus and optical disk
Abstract
In an optical disk system using a PRML identification system, a
method for deriving an optimum recording wave in a short period of
time is provided. Parameters of the recording wave are adjusted by
using an evaluation value obtained by a signal evaluation method
which is suitable for the PRML identification system as an index.
In this case, as a parameter adjusting method, a plurality of
adjusting methods are utilized.
Inventors: |
Kashihara, Yutaka;
(Chigasaki-shi, JP) ; Ogawa, Akihito;
(Kawasaki-shi, JP) ; Morishita, Naoki;
(Yokohama-shi, JP) ; Nakano, Masaki; (Tokyo,
JP) ; Ogawa, Masatsugu; (Tokyo, JP) ; Ookubo,
Shuichi; (Tokyo, JP) ; Iwanaga, Toshiaki;
(Tokyo, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Family ID: |
34939544 |
Appl. No.: |
11/143996 |
Filed: |
June 3, 2005 |
Current U.S.
Class: |
369/47.53 ;
369/47.5; 369/53.1; G9B/7.016; G9B/7.139 |
Current CPC
Class: |
G11B 20/10009 20130101;
G11B 20/10046 20130101; G11B 2220/2537 20130101; G11B 7/00456
20130101; G11B 20/10481 20130101; G11B 7/1267 20130101; G11B
20/10055 20130101; G11B 20/1012 20130101; G11B 7/1263 20130101 |
Class at
Publication: |
369/047.53 ;
369/047.5; 369/053.1 |
International
Class: |
G11B 005/09 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 3, 2004 |
JP |
2004-166191 |
Claims
What is claimed is:
1. An optical disk recording/reproducing method comprising:
determining a first recording parameter used to set a recording
waveform according to a first recording parameter adjusting method,
recording information on a medium by use of the first recording
parameter, deriving a first evaluation value of signal quality
based on a reproduction signal of the recording information by use
of a signal quality evaluating method, terminating a recording
parameter adjusting operation when the first evaluation value
satisfies a previously specified value, determining a second
recording parameter used to set a recording waveform according to a
second recording parameter adjusting method when the first
evaluation value does not satisfy the previously specified value,
recording information on the medium by use of the second recording
parameter, deriving a second evaluation value of signal quality
based on a reproduction signal of the recording information by use
of the signal quality evaluating method, terminating the recording
parameter adjusting operation when the second evaluation value
satisfies a previously specified value, and issuing an alarm when
the second evaluation value does not satisfy the previously
specified value.
2. The method according to claim 1, wherein the first recording
parameter adjusting method contains at least one of an adjusting
method which does not depend on a recording data bit string and an
adjusting method which depends on consecutive length of code bits
"1" of a recording data bit string and the second recording
parameter adjusting method is an adjusting method which depends on
consecutive length of code bits "1" of a recording data bit string
and consecutive length of code bits "0" adjacent thereto.
3. The method according to claim 1, wherein the signal quality
evaluating method contains at least two types of signal quality
evaluating methods.
4. The method according to claim 1, wherein the relation between
the recording parameter and the evaluation value is measured, an
optimum value of the evaluation value is derived based on the
measurement result and the recording parameter which causes the
evaluation value to be set to the optimum value is used as an
adjusting value.
5. The method according to claim 1, wherein the relation between
the recording parameter and the evaluation value is measured, an
optimum value of the evaluation value is derived based on the
measurement result, a certain value which is not larger than the
optimum value is used as a specified value, an upper limit value
and a lower limit value of the recording parameter which satisfies
the specified value are derived and an intermediate value between
the upper limit value and the lower limit value is used as a
recording parameter adjusting value.
6. The method according to claim 1, wherein the evaluation value
contains at least one of PRSNR (Partial Response Signal to Noise
Ratio) and SbER (Simulated bit Error Rate).
7. The method according to claim 1, wherein recording power based
on the recording waveform is adjusted in the first and second
recording parameter adjusting methods.
8. The method according to claim 1, wherein multi-pulse width based
on the recording waveform is adjusted in the first and second
recording parameter adjusting methods.
9. The method according to claim 1, wherein at least one of a
recording parameter of the shortest mark of the recording waveform
and a recording parameter of the second shortest mark is adjusted
in the first and second recording parameter adjusting methods.
10. The method according to claim 1, wherein at least one of a
first pulse, last pulse, single pulse and last cooling pulse of the
recording waveform is adjusted in the second recording parameter
adjusting method.
11. An optical disk recording/reproducing apparatus comprising:
means for determining a first recording parameter used to set a
recording waveform according to a first recording parameter
adjusting method, means for recording information on a medium by
use of the first recording parameter, means for deriving a first
evaluation value of signal quality based on a reproduction signal
of the recording information by use of a signal quality evaluating
method, means for terminating a recording parameter adjusting
operation when the first evaluation value satisfies a preset
specified value, means for determining a second recording parameter
used to set the recording waveform according to a second recording
parameter adjusting method when the first evaluation value does not
satisfy the preset specified value, means for recording information
on the medium by use of the second recording parameter, means for
deriving a second evaluation value of signal quality based on a
reproduction signal of the recording information by use of the
signal quality evaluating method, and means for terminating the
recording parameter adjusting operation when the second evaluation
value satisfies a preset specified value and issuing a warning when
the second evaluation value does not satisfy the preset specified
value.
12. The optical disk recording/reproducing apparatus according to
claim 11, wherein the means for determining the first and second
recording parameters adjusts recording power by use of the
recording waveform.
13. The optical disk recording/reproducing apparatus according to
claim 11, wherein the means for determining the first and second
recording parameters adjusts multi-pulse width by use of the
recording waveform.
14. The optical disk recording/reproducing apparatus according to
claim 11, wherein the means for determining the first and second
recording parameters adjusts at least one of a recording parameter
of the shortest mark of the recording waveform and a recording
parameter of the second shortest mark.
15. The optical disk recording/reproducing apparatus according to
claim 11, wherein the first and second evaluation values each
contain at least one of PRSNR (Partial Response Signal to Noise
Ratio) and SbER (Simulated bit Error Rate).
16. An optical disk comprising: marks and spaces recorded on a
recording track, wherein recording information is recorded by
arranging the marks and spaces on the recording track, the mark
being formed by applying laser light which is generated by
supplying an electrical recording wave to a laser diode, levels of
peak power, first bias power smaller than the peak power, second
bias power smaller than the first bias power and third power which
is minimum and smaller than the second bias power are defined as
parameters in an amplitude direction of the recording wave, a time
period T.sub.MP of the smallest pulse in a multi-pulse portion, a
time period T.sub.SFP ranging from a rise of the recording
information to a first rise of a first pulse of the recording wave,
a time period T.sub.EFP ranging from the rise of the recording
information to a first fall of the first pulse of the recording
wave, a time period T.sub.ELP in which a rise time period of a last
pulse of the recording wave ends immediately before the fall of the
recording information, and a time period T.sub.LC of a cooling
pulse of the recording wave following the fall of the recording
information are defined as parameters in a time-base direction, and
initial values of the parameters in the amplitude direction and the
parameters in the time-base direction are recorded when actual
parameters are determined.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from prior Japanese Patent Application No. 2004-166191,
filed Jun. 3, 2004, the entire contents of which are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to an optical disk
recording/reproducing method, optical disk recording/reproducing
apparatus and optical disk and more particularly to parameter
adjustment at the recording time of a signal on an optical disk and
at the reproducing time of a signal from the optical disk.
[0004] 2. Description of the Related Art
[0005] When information is recorded on an optical disk, a laser
beam is used. At this time, it is required to optimize the
recording power of the laser beam. As the technique for optimizing
the recording power, the technique disclosed in Jpn. Pat. Appln.
KOKAI Publication No. H4-141827 is provided.
[0006] In Jpn. Pat. Appln. KOKAI Publication No. H4-141827,
information is recorded and the amplitude of a reproduction signal
obtained at this time is measured while the recording power is
gradually changed. An optimum value of the recording power is
derived based on the relation between the recording power and the
amplitude of the reproduction signal. Further, information is
recorded and the bit error rate obtained at this time is measured
while the recording power is gradually changed. An optimum value of
the recording power is derived based on the relation between the
recording power and the bit error rate. The recording waveform of
an electrical signal to generate a laser beam takes a so-called
multi-pulse form which is repeatedly set at high and low levels in
a short period of time. If the laser beam obtained by use of the
recording waveform is applied to a track of the optical disk, marks
are formed. Data contents are expressed by the widths of marks and
spaces arranged on the track.
[0007] As the technique using the relation between the first and
last pulses of the recording wave of the multi-pulse form, the
technique disclosed in Jpn. Pat. Appln. KOKAI Publication No.
2000-149262 is provided. In this case, the first pulse of the
recording wave of the multi-pulse form is called the first pulse
and the last pulse thereof is called the last pulse. In Jpn. Pat.
Appln. KOKAI Publication No. 2000-149262, the recording waveform is
divided into pattern groups by using the length of each mark to be
recorded and the length of a space preceding (or succeeding to) the
mark as a pair and the width of the first pulse (or last pulse) is
optimized for each pattern group. Information is recorded by
changing the width of the first pulse (or last pulse) and the
amount of jitter occurring at this time is measured. The jitter
amount is a variation in time at which the reproduction signal
passes through a slice level set in a level slicer. The optimum
value of the width of the first pulse (or last pulse) is derived
based on the relation between the width of the first pulse (or last
pulse) and the jitter amount.
[0008] As a system for reproducing information recorded on the
optical disk, a slice and identification system and PRML (Partial
Response and Maximum Likelihood) identification system are
provided.
[0009] Simply speaking, the slice and identification system
converts reflection light reflected from the optical disk into an
electrical signal by use of the photoelectric converter of a pickup
head. The electrical signal is sliced in the slice circuit and
converted into decoded binary data.
[0010] The PRML identification system is as follows. In the PRML
identification system, a PR (Partial Response) characteristic
corresponding to the recording/reproducing characteristic is used.
As an example, a PR(1, 2, 2, 2, 1) characteristic is explained. The
PR(1, 2, 2, 2, 1) characteristic indicates a characteristic in
which a reproduction signal corresponding to a code bit "1" is set
to "12221". A reproduction signal is obtained by the convolution
operation for the code bit series and the series of "12221"
indicating the PR characteristic. For example, a reproduction
signal for the code bit series "0100000000" is set to "0122210000".
Likewise, a reproduction signal for the code bit series
"0110000000" is set to "0134431000", a reproduction signal for the
code bit series "0111000000" is set to "0135653100", a reproduction
signal for the code bit series "0111100000" is set to "00135775310"
and a reproduction signal for the code bit series "0111110000" is
set to "0135787531". In the PR(1,2,2,2,1) characteristic, the
reproduction signal is set to nine levels. The reproduction signal
calculated by the convolution operation is an ideal reproduction
signal (which is hereinafter referred to as a pass). However, in
the actual reproduction signal, the characteristic is not always
exactly set to the PR(1,2,2,2,1) characteristic and the
reproduction signal contains deterioration factors such as noises.
In the PRML identification system, the characteristic of a
reproduction signal is set closer to the PR characteristic by use
of an equalizer. The reproduction signal with the characteristic
set closer to the PR characteristic is called an equalized
reproduction signal. After this, a pass having the minimum
Euclidean distance with respect to the equalized reproduction
signal is selected by use of a Viterbi decoder. The pass and code
bit series are set in a one-to-one correspondence. The Viterbi
decoder outputs a code bit series corresponding to the selected
pass as decoded binary data.
[0011] Recently, with an increase in the density of the optical
disk, the PRML identification system is more frequently used
instead of the slice and identification system.
[0012] In the optical disk system using the PRML identification
system, it is assumed that the reproduction signal is not a binary
signal but a signal with a three or more values or a so-called
multi-value signal. The amplitude of the reproduction signal is a
difference in level between the maximum and minimum values of the
reproduction signal. A method for optimizing the recording waveform
based on the measured value of the amplitude of the reproduction
signal is a method based on the assumption that the reproduction
signal is a binary signal. That is, the recording waveform is
different from the recording waveform optimum for the optical disk
system using the PRML identification system.
[0013] In the optical disk system using the PRML identification
system, a reduction in the jitter amount does not always lead to
enhancement of the quality of the reproduction signal. That is, the
recording waveform cannot always be optimized by using the
measurements of the jitter amount.
[0014] In the measurement of the bit error rate, measured values
greatly vary due to local defects of the optical disk. Therefore,
the recording waveform cannot be sufficiently optimized by use of
the method for optimizing the recording waveform based on the
measured values of the bit error rate because of an influence by a
variation in the bit error rate. Further, in order to measure the
bit error rate, it is necessary to record/reproduce an extremely
long code bit series on the optical disk. Therefore, the method for
optimizing the recording waveform based on the measured values of
the bit error rate requires a long time for optimizing the
recording waveform.
BRIEF SUMMARY OF THE INVENTION
[0015] An object of the embodiments of this invention is to provide
a method for deriving an optimum recording waveform in an optical
disk system using the PRML identification system.
[0016] Another object of this invention is to provide a method for
optimizing the recording waveform in a short period of time in the
optical disk system using the PRML identification system.
[0017] Further, still another object of this invention is to
provide an optical disk recording/reproducing apparatus capable of
performing an optimum recording/ reproducing operation in the
optical disk system using the PRML identification system.
[0018] Another object of this invention is to provide an optical
disk on which information is recorded by use of an optimum
recording waveform in the optical disk system using the PRML
identification system.
[0019] In order to attain the above objects, in one embodiment
described below, a first recording parameter is determined
according to a first recording parameter adjusting method,
information is recorded on a medium by use of the first recording
parameter, an evaluation value of the signal quality is derived
from the reproduction signal by a signal quality evaluation method,
the operation of adjusting the recording parameter is terminated
(for example, steps S1 to S4 in FIG. 3) when the evaluation value
satisfies a previously specified value, a second recording
parameter is determined according to a second recording parameter
adjusting method when the evaluation value does not satisfy the
previously specified value, information is recorded on the medium
by use of the second recording parameter, an evaluation value of
the signal quality is derived from the reproduction signal by the
signal quality evaluation method, the operation of adjusting the
recording parameter is terminated when the evaluation value
satisfies a previously specified value, and an alarm is issued when
the evaluation value does not satisfy the previously specified
value (for example, steps S5 to S6 in FIG. 3).
[0020] In the optical disk system using the PRML identification
system, an optimum recording parameter can be attained by use of
the above optical disk recording/reproducing method.
[0021] In the optical disk system using the PRML identification
system, a recording parameter can be attained in a short period of
time by use of the above optical disk recording/reproducing
method.
[0022] Further, an optical disk recording/reproducing apparatus
which can correctly record/reproduce information by using a
recording waveform derived by the optical disk
recording/reproducing method can be provided.
[0023] In addition, an optical disk on which information is
correctly recorded by recording information by use of a recording
waveform derived by the optical disk recording/reproducing method
can be provided.
[0024] Additional objects and advantages of the embodiments will be
set forth in the description which follows, and in part will be
obvious from the description, or may be learned by practice of the
invention. The objects and advantages of the invention may be
realized and obtained by means of the instrumentalities and
combinations particularly pointed out hereinafter.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0025] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate embodiments of
the invention, and together with the general description given
above and the detailed description of the embodiments given below,
serve to explain the principles of the invention.
[0026] FIG. 1 is a block diagram showing one example of an optical
disk recording/reproducing apparatus of this invention;
[0027] FIG. 2 is an explanatory diagram showing an example of a
recording waveform according to this invention;
[0028] FIG. 3 is a flowchart for illustrating an example of an
optical disk recording/reproducing method according to this
invention;
[0029] FIG. 4 is an explanatory diagram showing an example of a
recording power adjusting method;
[0030] FIG. 5 is an explanatory diagram for illustrating an
intermediate multi-pulse width adjusting method;
[0031] FIG. 6 is an explanatory diagram for illustrating a first
pulse width adjusting method at the 2T mark recording time;
[0032] FIG. 7 is an explanatory diagram for illustrating a first
pulse width adjusting method at the 3T mark recording time;
[0033] FIG. 8 is a block diagram showing an example of the
configuration of a PRSNR calculator;
[0034] FIG. 9 is a first explanatory diagram showing the basic
principle of SbER;
[0035] FIG. 10 is a second explanatory diagram showing the basic
principle of SbER;
[0036] FIG. 11 is a block diagram showing an example of the
configuration of an SbER calculator;
[0037] FIG. 12 is a block diagram showing an example of the
configuration of an adaptive control value calculator;
[0038] FIG. 13 is a first explanatory diagram showing the basic
principle of an adaptive control value;
[0039] FIGS. 14A and 14B are second explanatory diagrams showing
the basic principle of an adaptive control value;
[0040] FIG. 15 is a third explanatory diagram showing the basic
principle of an adaptive control value;
[0041] FIG. 16 is a flowchart for illustrating an example of a
second optical disk recording/reproducing method according to this
invention;
[0042] FIG. 17 is a diagram showing an example of a second
recording waveform of this invention;
[0043] FIG. 18 is a flowchart for illustrating an example of a
third optical disk recording/reproducing method according to this
invention;
[0044] FIG. 19 is a flowchart for illustrating an example of a
fourth optical disk recording/reproducing method according to this
invention; and
[0045] FIG. 20 is a diagram showing an example of a third recording
waveform of this invention.
DETAILED DESCRIPTION OF THE INVENTION
[0046] There will now be described embodiments of an optical disk
recording/reproducing apparatus, recording method and optical disk
medium according to this invention with reference to the
accompanying drawings.
[0047] FIG. 1 is a block diagram showing an optical disk
recording/reproducing apparatus. Recording binary data is converted
into a series in which at least two "0s" or "1s" in the code bit
series successively occur by use of a modulator (not shown) whose
run length is "1". The recording binary data is converted into a
recording wave according to a recording parameter output from a
controller 102 by use of a laser diode (LD) driver 101. The
recording wave of an electrical signal is converted into an optical
signal by a pickup head (PUH) 103 and then applied onto an optical
disk 100. On the optical disk 100, marks are formed according to
application of the laser light. As the optical disk 100, a land
& groove recording type optical disk is used.
[0048] At the reproduction time, information recorded on the
optical disk 100 is reproduced as a weak analog signal by use of
the PUH 103. The analog signal is amplified to a sufficiently high
signal level by use of a preamplifier 104 and then converted into a
digital signal sampled at a constant frequency by an analog-digital
converter (ADC) 105. A digital reproduction signal is converted
into a signal which is synchronized with a channel clock in an
equalizer 106 containing a phase-locked loop (PLL) and, at the same
time, it is converted into an equalized reproduction signal of a
characteristic which is close to the PR(1,2,2,2,1) characteristic.
The equalization coefficient used in the equalizer 106 is derived
from the signal which is synchronized with the channel clock and
decoded binary data.
[0049] After this, in a Viterbi decoder 107, a pass is selected.
The Euclidean distance of the pass with respect to the equalized
reproduction signal is minimum and a code bit series corresponding
to the selected pass is output as decoded binary data.
[0050] The equalized reproduction signal and decoded binary data
are input to a PRSNR (Partial Response Signal to Noise Ratio)
calculator 108 and an evaluation value PRSNR is measured. Further,
the equalized reproduction signal and decoded binary data are also
input to an SbER (Simulated bit Error Rate) calculator 109 and an
evaluation value SbER is measured. In addition, the equalized
reproduction signal and decoded binary data are input to an
adaptive control value calculator 110 and an adaptive control value
is measured. The measured PRSNR, SbER and adaptive control value
are supplied to the controller 102 and the evaluation value is
evaluated. Further, the recording parameter is adjusted and
modified. In addition, the first and second recording parameter
adjusting methods are selectively switched. Although not shown in
the drawing, an alarm signal is output to warning means as
required.
[0051] Further, as will be described in detail later, the relation
between the recording parameter and the evaluation value is
measured in the controller 102, the optimum value of the evaluation
values is derived based on the measurement result and the recording
parameter which causes the evaluation value to be set as the
optimum value can be determined as an adjusted value. In addition,
in the controller 102, the relation between the recording parameter
and the evaluation value is measured, the optimum value of the
evaluation values is derived based on the result of measurement and
a certain value smaller than or equal to the optimum value may be
set as a specified value. Then, the upper limit value and lower
limit value of the recording parameters which satisfy the specified
value are determined and an intermediate value of the upper limit
and lower limit values is set as an adjusted value of the recording
parameter.
[0052] (Recording Waveform)
[0053] FIG. 2 shows the configurations of recording binary data a
and recording waveform b. Marks are formed on the optical disk in
correspondence to high levels of the recording binary data ("a" in
FIG. 2). The recording waveform b contains a single pulse to record
the shortest 2T mark. As a mark to be recorded becomes longer, the
number of pulses of the recording waveform b becomes larger. The
recording parameters are individually set when information is
recorded on the land track and when information is recorded on the
groove track. The recording parameters are shown in the TABLE
1.
1 TABLE 1 Recording Peak Power, Bias Power 1, Bias Parameter Power
2, Bias Power 3, T.sub.SFP, for Land Track T.sub.EFP, T.sub.MP,
T.sub.SLP, T.sub.ELP, T.sub.LC Recording Peak Power, Bias Power 1,
Bias Parameter Power 2, Bias Power 3, T.sub.SFP, for Groove Track
T.sub.EFP, T.sub.MP, T.sub.SLP, T.sub.ELP, T.sub.LC
[0054] T.sub.LC, T.sub.SFP, T.sub.ELP among the recording
parameters in the time-base direction are adaptive control
parameters. That is, the mark length and space length are
classified into three groups of 2T, 3T and .gtoreq.4T (.gtoreq.4T
indicates the length larger than or equal to 4T) and individual
parameters are set for respective groups. Values different for
respective mark lengths can be set for T.sub.LC. Further, values
different for respective mark lengths and the lengths of spaces
preceding the marks can be set for T.sub.SFP. Likewise, values
different for respective mark lengths and the lengths of spaces
succeeding to the marks can be set for T.sub.ELP. The adaptive
control parameters are shown in the TABLE 2.
2 TABLE 2 Mark Length 2T 3T .gtoreq.4T T.sub.LC for Land al bl cl
Track T.sub.SFP for Land Track Preceding 2T dl el fl Space 3T gl hl
il Length .gtoreq.4T jl kl ll T.sub.ELP for Land Track Succeeding
2T ml nl ol Space 3T pl ql rl Length .gtoreq.4T sl tl ul T.sub.LC
for Groove ag bg cg Track T.sub.SFP for Groove Track Preceding 2T
dg eg fg Space 3T gg hg ig Length .gtoreq.4T jg kg lg T.sub.ELP for
Groove Track Succeeding 2T mg ng og Space 3T pg qg rg Length
.gtoreq.4T sg tg ug
[0055] (Recording Parameter Adjusting Procedure)
[0056] The recording parameter adjusting procedure is explained.
Since the adjusting procedures for the land track recording
parameters and groove track recording parameters are the same, only
the land track recording parameter adjusting procedure is explained
here. The outline of the adjusting procedure is shown in FIG.
3.
[0057] (Adjustment of Peak Power and Bias Power 1: Step S1 in FIG.
3)
[0058] 1. The peak power is set to an initial value P.sub.P0.
P.sub.P0 is previously recorded in a preset position on the optical
disk. A value in a corresponding portion is reproduced and the thus
attained value is set. Likewise, the bias power 1, bias power 2 and
bias power 3 are set to initial values P.sub.B10, P.sub.B20 and
P.sub.B30. The initial values P.sub.B10, P.sub.B20, P.sub.B30 are
previously recorded in preset positions on the optical disk.
Likewise, the time-base parameters T.sub.SFP, T.sub.EFP, T.sub.MP,
T.sub.SLP, T.sub.ELP, T.sub.LC are set to initial values. The
initial values of the time-base parameters are previously recorded
in preset positions on the optical disk. In this example, the peak
power and bias power 1 are treated as variables.
[0059] 2. After random data is successively recorded ten times on a
certain track, the random data is reproduced to derive an
equalization coefficient. In the succeeding procedure, the thus
derived equalization coefficient is used.
[0060] 3. Random data is successively recorded ten times on a
certain track. The operation of successively recording random data
ten times is performed each time the peak power and bias power 1
are adjusted. PRSNR is measured each time the peak power and bias
power 1 are adjusted. The peak power and bias power 1 are adjusted
so as to increase PRSNR. The adjusting operation is performed to
set the ratio of the peak power to the bias power 1 equal to that
of P.sub.P0 to P.sub.B10.
[0061] 4. The relation between the peak power and PRSNR is derived
in the procedure 3 (refer to FIG. 4).
[0062] 5. The maximum value of PRSNR is derived.
[0063] 6. The upper limit value P.sub.POU and the lower limit value
P.sub.POL of the peak power which is set to 80% or more of the
maximum value of PRSNR are derived.
[0064] 7. The adjusted value P.sub.P1 of the peak power and the
adjusted value P.sub.B11 of the bias power 1 are derived according
to the following equations.
P.sub.P1=(P.sub.POL+P.sub.POU)/2
P.sub.B11=(P.sub.B10/P.sub.P0).times.P.sub.P1
[0065] An adjusting method of setting the maximum value of PRSNR
derived in the procedure 5 to P.sub.P1 may be used. In the
procedure 6, the specified value is set to 80% or more of the
maximum value, but this is not limitative. Further, PRSNR is set as
an evaluation value, but SbER may be used as an evaluation value.
When SbER is used as the evaluation value, the peak power and bias
power 1 are adjusted to make the SbER value smaller.
[0066] (Adjustment of T.sub.MP: Step S2 in FIG. 3)
[0067] 1. The peak power is set to P.sub.P1. The bias power 1, bias
power 2 and bias power 3 are set to P.sub.B11, P.sub.B20 and
P.sub.B30. The time-base parameters T.sub.SFP, T.sub.EFP, T.sub.MP,
T.sub.SLP, T.sub.ELP, T.sub.LC are set to initial values. In this
example, T.sub.MP is treated as a variable.
[0068] 2. Random data is successively recorded ten times on a
certain track. The operation of successively recording random data
ten times is performed each time T.sub.MP is adjusted. PRSNR is
measured each time T.sub.MP is adjusted. T.sub.MP is adjusted so as
to increase PRSNR.
[0069] 3. The relation between T.sub.MP and PRSNR is derived in the
procedure 2 (refer to FIG. 5).
[0070] 4. The maximum value of PRSNR is derived.
[0071] 5. The upper limit value P.sub.MPU and the lower limit value
P.sub.MPL of T.sub.MP which is set to 80% or more of the maximum
value of PRSNR are derived.
[0072] 6. The adjusted value T.sub.MP(cal) of T.sub.MP is derived
according to the following equation.
T.sub.MP(cal)=(T.sub.MPL+T.sub.MPU)/2
[0073] An adjusting method for setting the maximum value of PRSNR
derived in the procedure 4 to T.sub.MP(cal) may be used. In the
procedure 5, the specified value is set to 80% or more of the
maximum value, but this is not limitative. Further, PRSNR is set as
an evaluation value, but SbER may be used as an evaluation value.
When SbER is used as the evaluation value, T.sub.MP is adjusted to
make the SbER value smaller.
[0074] (Adjustment of T.sub.SFP for 2T mark and T.sub.SFP for 3T
mark: Step S3 in FIG. 3)
[0075] 1. The peak power is set to P.sub.P1. The bias power 1, bias
power 2 and bias power 3 are set to P.sub.B11, P.sub.B20 and
P.sub.B30. T.sub.MP is set to T.sub.MP(cal). The other time-base
parameters T.sub.SFP, T.sub.EFP, T.sub.SLP, T.sub.ELP, T.sub.LC are
set to initial values. In this example, T.sub.SFP for a 2T mark and
T.sub.SFP for a 3T mark are treated as variables. The T.sub.SFP for
a 2T mark is expressed by dl, gl, jl in the TABLE 2. Likewise,
T.sub.SFP for a 3T mark is expressed by el, hl, kl in the TABLE
2.
[0076] 2. Random data is successively recorded ten times on a
certain track. The operation of successively recording random data
ten times is performed each time T.sub.SFP for a 2T mark is
adjusted. PRSNR is measured each time T.sub.SFP is adjusted.
T.sub.SFP is adjusted so as to increase PRSNR.
[0077] 3. The relation between T.sub.SFP and PRSNR is derived in
the procedure 2 (refer to FIG. 6).
[0078] 4. The maximum value of PRSNR is derived.
[0079] 5. The upper limit value P.sub.SFP2TU and the lower limit
value P.sub.SFP2TL of T.sub.SFP for the 2T mark which is set to 80%
or more of the maximum value of PRSNR are derived.
[0080] 6. The adjusted value T.sub.SFP2T of T.sub.SFP for the 2T
mark is derived according to the following equation.
T.sub.SFP2T=(T.sub.SFP2TL+T.sub.SFP2TU)/2
[0081] 7. Random data is successively recorded ten times on a
certain track. The operation of successively recording random data
ten times is performed each time T.sub.SFP for a 3T mark is
adjusted. PRSNR is measured each time T.sub.SFP is adjusted.
T.sub.SFP is adjusted so as to increase PRSNR.
[0082] 8. The relation between T.sub.SFP and PRSNR is derived in
the procedure 7 (refer to FIG. 7).
[0083] 9. The maximum value of PRSNR is derived.
[0084] 10. The upper limit value P.sub.SFP3TU and the lower limit
value P.sub.SFP3TL of T.sub.SFP for the 3T mark which is set to 80%
or more of the maximum value of PRSNR are derived.
[0085] 11. The adjusted value T.sub.SFP3T of T.sub.SFP for the 3T
mark is derived according to the following equation.
T.sub.SFP3T=(T.sub.SFP3TL+T.sub.SFP3TU)/2
[0086] An adjusting method for setting the maximum value of PRSNR
derived in the procedure 4 to T.sub.SFP2T and setting the maximum
value of PRSNR derived in the procedure 9 to T.sub.SFP3T may be
used. In the procedures 5 and 10, the specified value is set to 80%
or more of the maximum value, but this is not limitative. Further,
PRSNR is set as an evaluation value, but SbER may be used as an
evaluation value. When SbER is used as the evaluation value,
T.sub.SFP is adjusted to make the SbER value smaller.
[0087] (Determination as to Whether PRSNR and SbER Satisfy
Specified Standard Value or Not: Step S4 in FIG. 3)
[0088] 1. The peak power is set to P.sub.P1. The bias power 1, bias
power 2 and bias power 3 are set to P.sub.B11, P.sub.B20 and
P.sub.B30. T.sub.MP is set to T.sub.MP(cal). T.sub.SFP for the 2T
mark is set to T.sub.SFP2T. T.sub.SFP for the 3T mark is set to
T.sub.SFP3T. The other time-base parameters T.sub.SFP, T.sub.EFP,
T.sub.SLP, T.sub.ELP, T.sub.LC are set to initial values.
[0089] 2. Random data is successively recorded ten times on five
adjacent tracks.
[0090] 3. Data recorded on a central one of the tracks used in the
procedure 2 is reproduced and an equalization coefficient is
derived. In the succeeding procedure, the thus derived equalization
coefficient is used.
[0091] 4. PRSNR and SbER are measured.
[0092] 5. If PRSNR is set more than or equal to 15.0 and SbER is
set less than or equal to 5.times.10.sup.-5, the recording
parameters set in the procedure 1 are used as parameters obtained
after adjustment and then the recording parameter adjusting
procedure is terminated. If PRSNR is less than 15.0 or SbER is
larger than 5.times.10.sup.-5, the following adaptive control
parameter adjusting procedure is performed.
[0093] In the procedure 5, PRSNR is set more than or equal to 15.0
and SbER is set less than or equal to 5.times.10.sup.-5, but this
invention is not limited to this case. For example, PRSNR may be
set more than or equal to 13.0 and SbER may be set less than or
equal to or 5.times.10.sup.-4.
[0094] (Adjustment of Adaptive Control Parameters T.sub.SFP,
T.sub.ELP: Step S5 in FIG. 3)
[0095] 1. The peak power is set to P.sub.P1. The bias power 1, bias
power 2 and bias power 3 are set to P.sub.B11, P.sub.B20 and
P.sub.B30. T.sub.MP is set to T.sub.MP(cal). T.sub.SFP for the 2T
mark is set to T.sub.SFP2T. T.sub.SFP for the 3T mark is set to
T.sub.SFP3T. The other time-base parameters T.sub.SFP, T.sub.EFP,
T.sub.SLP, T.sub.ELP, T.sub.LC are set to initial values. In this
example, nine types of T.sub.SFP, T.sub.EFP classified according to
the mark length and space length, that is, dl, el, fl, gl, hl, il
jl, kl, ll, ml, nl, ol, pl, q1, rl, sl, tl, ul in the TABLE 2 are
independently adjusted.
[0096] 2. Random data of the length longer than or equal to 928512
channel bits is successively recorded ten times on a certain track.
The operation of successively recording random data ten times is
performed each time T.sub.SFP, T.sub.ELP are adjusted.
[0097] 3. The adaptive control value is measured. The adaptive
control value is calculated for each of nine types of T.sub.SFP,
T.sub.ELP and the value is set to +1, 0 or -1.
[0098] 4. If the adaptive control value for certain T.sub.SFP
(T.sub.ELP) is +1, T.sub.SFP (T.sub.ELP) is reduced (increased) by
time .DELTA.T. If the adaptive control value for certain T.sub.SFP
(T.sub.ELP) is -1, T.sub.SFP (T.sub.ELP) is increased (reduced) by
time .DELTA.T. In this case, .DELTA.T is T/32.
[0099] 5. The procedures 2 to 4 are repeatedly performed until all
of the adaptive control values are set to 0. If all of the adaptive
control values are set to 0, T.sub.SFP and T.sub.ELP obtained at
this time are respectively set to T.sub.SFP(cal) and
T.sub.ELP(cal).
[0100] In the above case, the procedures are repeatedly performed
until all of the adaptive control values are set to 0, but this
invention is not limited to this case. For example, the procedures
may be repeatedly performed until 80% or more of the control values
are set to 0. Alternatively, the procedures may be repeatedly
performed until the control values are set to as close to 0 as
possible. Further, the number of repetition times is previously
specified and the procedures may be repeatedly performed by the
specified number of times.
[0101] The adaptive control value is set to one of three types of
[-1, 0, +1], but this invention is not limited to this case. For
example, the adaptive control value is set to one of five types of
[-2, --1, 0, +1, +2].
[0102] Further, .DELTA.T is set to T/32, but this is not limitative
and .DELTA.T may be set to T/16, for example.
[0103] (Features of First Half and Latter Half of Data Processing
Flow of FIG. 3)
[0104] The first half is a first recording parameter adjusting
method and is one of or both of an adjusting method which is
independent of a recording data bit string and an adjusting method
which is dependent on the run length (consecutive length) of a code
bit "1" of the recording data bit string. The latter half is a
second recording parameter adjusting method and is an adjusting
method which is dependent on the run length of a code bit "1" of
the recording data bit string and the run length of a code bit "0"
adjacent thereto.
[0105] (Determination as to whether Optical Disk is Improper or
Not)
[0106] 1. The peak power is set to P.sub.P1. The bias power 1, bias
power 2 and bias power 3 are set to P.sub.B11, P.sub.B20 and
P.sub.B30. T.sub.MP, T.sub.SFP, T.sub.ELP are set to T.sub.MP(cal),
T.sub.SFP(cal), T.sub.ELP(cal). The other time-base parameters
T.sub.EFP, T.sub.ELP, T.sub.LC are set to initial values.
[0107] 2. Random data is successively recorded ten times on five
adjacent tracks.
[0108] 3. Data recorded on a central one of the tracks used in the
procedure 2 is reproduced and an equalization coefficient is
derived. In the succeeding procedure, the thus derived equalization
coefficient is used.
[0109] 4. PRSNR and SbER are measured.
[0110] 5. If PRSNR is set equal to or more than 15.0 and SbER is
set equal to or less than 5.times.10.sup.-5, the recording
parameters set in the procedure 1 are used as parameters obtained
after adjustment and then the recording parameter adjusting
procedure is terminated. If PRSNR is less than 15.0 or SbER is
larger than 5.times.10.sup.-5, the optical disk is determined as an
improper optical disk and discharged.
[0111] In the procedure 5, PRSNR is set equal to or more than 15.0
and SbER is set equal to or less than 5.times.10.sup.-5, but this
invention is not limited to this case. For example, PRSNR may be
set equal to or more than 13.0 and SbER may be set equal to or less
than 5.times.10.sup.-4.
[0112] (Explanation of PRSNR)
[0113] PRSNR used for calculation of the recording parameters is
explained. A detection error tends to occur in the Viterbi decoding
process when the Euclidean distance between passes is short. The
Euclidean distance d between different passes is defined by
d.sup.2=.SIGMA..epsilon..sub.i.sup.2. In this case, it is assumed
that a polynomial defined by a code bit series b.sub.k
corresponding to one of the passes is set to
B(D)=.SIGMA.b.sub.kD.sub.k, a polynomial defined by a code bit
series c.sub.k (b.sub.k, c.sub.k are set to 0 or 1) corresponding
to the other pass is set to C(D)=.SIGMA.c.sub.kD.sub.k, a
polynomial which defines a partial response is set to
H(D)=.SIGMA.h.sub.kD.sub.k, and
N(D)=(B(D)-C(D))*H(D)=.SIGMA..epsilon..su- b.iD.sub.i. In this
case, D indicates a time delay operator using a channel clock time
as a unit and h.sub.k indicates a preset partial response
characteristic and h.sub.0=1, h.sub.1=2, h.sub.2=2, h.sub.3=2,
h.sub.4=1 and h.sub.5 and succeeding values are all set to 0.
Further, a symbol * indicates an operator of the convolution
operation. The Euclidean distance between the passes corresponds to
a signal component in a system using the PRML identification
system.
[0114] In a system having a combination of the PR(1,2,2,2,1)
characteristic and recording binary data of the minimum run length
l, .epsilon..sub.i and d.sup.2 in the small Euclidean distance
between the passes are obtained as shown in the TABLE 3.
3TABLE 3 Pattern .epsilon..sub.i d.sup.2 1 12221 14 2 1210-1-2-1 12
3 121000121 12 4 12100000-1-2-1 12 5 1210000000-1-2-1 12 6
121000000000121 12
[0115] A difference P(D).multidot.Y(D)=.SIGMA.v.sub.kD.sub.k
between the polynomial Y(D)=.SIGMA.y.sub.kD.sub.k defined by the
equalized reproduction signal y.sub.k and the pass P(D)=A(D)*H(D)
corresponding to the polynomial A(D)=.SIGMA.a.sub.kD.sub.k defined
by the decoded binary data a.sub.k is called an equalized
difference. The influence given by the equalized difference on the
pattern 1 can be expressed as follows.
.SIGMA.(v.sub.k+2v.sub.k+1+2v.sub.k+2+2v.sub.k+3+v.sub.k+4).sup.2=N*(14R.s-
ub.0+24R.sub.1+16R.sub.2+8R.sub.3+2R.sub.4) (R.sub.1 is defined as
.SIGMA.v.sub.kv.sub.k+i/N)
[0116] Further, the influence corresponds to a noise component for
the pattern 1. Likewise, the influences given by the equalized
difference on the patterns 2, 3 can be expressed as follows.
.SIGMA.(v.sub.k+2v.sub.k+1+v.sub.k+2-v.sub.k+4-2v.sub.k+3-v.sub.k+4).sup.2-
=N*(12R.sub.0+16R.sub.1+2R.sub.2-8R.sub.3-12R.sub.4-8R.sub.5-2R.sub.6)
.SIGMA.(v.sub.k+2v.sub.k+1+v.sub.k+2+v.sub.k+6+2v.sub.k+7+v.sub.k+8).sup.2-
=N*(12R.sub.0+16R.sub.1+4R.sub.2+2R.sub.4+8R.sub.5+12R.sub.6+8R.sub.7+2R.s-
ub.8)
[0117] Further, the influences correspond to noise components for
the patterns 2, 3.
[0118] Therefore, the signal/noise ratio S1 of the pattern 1 can be
given as follows. 1 S1 = 14 .times. 14 14 R 0 + 24 R 1 + 16 R 2 + 8
R 3 + 2 R 4 = 14 R 0 + ( 12 R 1 + 8 R 2 + 4 R 3 + R 4 ) / 7
[0119] Likewise, the signal/noise ratios S2, S3 of the patterns 2,
3 can be given as follows. 2 S2 = 12 .times. 12 12 R 0 + 16 R 1 + 2
R 2 - 8 R 3 - 12 R 4 - 8 R 5 - 2 R 6 = 12 R 0 + ( 8 R 1 + R 2 - 4 R
3 - 6 R 4 - 4 R 5 - R 6 ) / 6 S3 = 12 .times. 12 12 R 0 + 16 R 1 +
4 R 2 + 2 R 4 + 8 R 5 + 12 R 6 + 8 R 7 + 2 R 8 = 12 R 0 + ( 8 R 1 +
2 R 2 + R 4 + 4 R 5 + 6 R 6 + 4 R 7 + R 8 ) / 6
[0120] As the signal/noise ratio is lower, the quality of the
reproduction signal is worse. The lowest one of S1, S2, S3 is used
as PRSNR.
[0121] A concrete internal block diagram of the PRSNR calculator
108 is shown in FIG. 8. As PRSNR is higher, the signal quality
becomes higher, and therefore, the recording parameter may be
adjusted so as to increase PRSNR.
[0122] The signal/noise ratios of the patterns 4, 5, 6 can be
derived in the same manner. Therefore, the signal/noise ratios of
the patterns 1 to 6 are derived and the minimum value thereof can
be used as PRSNR. However, in general, the frequency of occurrence
of the patterns 4, 5, 6 is lower than that of the patterns 1, 2, 3.
For easy measurement, in this embodiment, PRSNR is derived based on
the patterns 1, 2, 3. Further, the signal/noise ratio of a pattern
having a larger Euclidean distance between the passes can be
derived in the same manner. In order to more precisely evaluate the
signal quality, PRSNR can be derived together with the signal/noise
ratio with respect to the patterns.
[0123] In FIG. 8, a reference symbol 301 denotes a target signal
generator which generates a target signal by use of the PR waveform
and decoded binary data. A reference symbol 302 denotes a
comparator which compares the target signal with an equalized
reproduction signal to derive an equalized difference. The above
operation process is performed by use of the equalized difference.
The autocorrelation of the equalized difference is calculated and
weighted by a multiplier by using .beta.i. Then, the sum of the
correlation values is derived.
[0124] (Explanation of SbER)
[0125] Next, SbER used for calculation of the recording parameter
is explained. In the PRSNR identification system, a probability
that a recording binary pattern T is erroneously identified as a
different binary pattern F is considered. When the equalized
reproduction signal is S and the passes of the patterns T, F are
PT, PF (refer to FIG. 9), the condition in which the pattern T is
erroneously identified as the pattern F is expressed by the
following equation.
D=E.sub.PF,S.sup.2-E.sub.PT,S.sup.2<0
[0126] where E.sub.PF,S indicates an Euclidean distance between the
pass PF and the reproduction signal S and E.sub.PT,S indicates an
Euclidean distance between the pass PT and the reproduction signal
S. The Euclidean distance between the signals P1 and P2 is given by
the following equation. 3 E P1 , P2 = i ( P1 i - P2 i ) 2
[0127] If the distribution of accumulated D values (refer to FIG.
10) indicates a normal distribution and the mean value and standard
deviation value thereof are respectively set to .mu. and .sigma.,
the probability F(0) that T is erroneously identified as F can be
expressed as follows. 4 F ( 0 ) = - .infin. 0 exp { - ( x - ) 2 / 2
2 } 2 x
[0128] By deriving F(0) with respect to the pattern pair T, F in
which errors tend to occur as shown in the TABLE 4, an estimated
value SbER of bER (bit error) can be derived as follows.
SbER=.SIGMA.C.sub.T.multidot.F(0).multidot.H.sub.T,F
[0129] where C.sub.T indicates the rate of occurrence of the
pattern T and H.sub.T,F indicates a humming distance.
[0130] FIG. 11 is a concrete internal block diagram of the SbER
calculator 109. Decoded binary data is input to a pattern
comparator 401. The pattern comparator 401 compares patterns
recorded in a reference TABLE 402 with the decoded binary data to
detect a pattern which tends to be erroneously identified. The
detected pattern is input to an operator 403. The reproduction
signal is input to the operator 403 via a register 404. Thus, the
operation shown by the above equation is carried out to derive
SbER.
4 TABLE 4 Pattern T(F) Pattern F(T) H.sub.T,F 1 001110000 001100000
1 2 011110000 011100000 1 3 111110000 111100000 1 4 001110001
001100001 1 5 011110001 011100001 1 6 111110001 111100001 1 7
001110011 001100011 1 8 011110011 011100011 1 9 111110011 111100011
1 10 000011100 000001100 1 11 000011110 000001110 1 12 000011111
000001111 1 13 100011100 100001100 1 14 100011110 100001110 1 15
100011111 100001111 1 16 110011100 110001100 1 17 110011110
110001110 1 18 110011111 110001111 1 19 00111001100 00110011100 2
20 01111001100 01110011100 2 21 11111001100 11110011100 2 22
00111001110 00110011110 2 23 01111001110 01110011110 2 24
11111001110 11110011110 2 25 00111001111 00110011111 2 26
01111001111 01110011111 2 27 11111001111 11110011111 2 28
00001100000 00000110000 2 29 10001100000 10000110000 2 30
11001100000 11000110000 2 31 00001100001 00000110001 2 32
10001100001 10000110001 2 33 11001100001 11000110001 2 34
00001100011 00000110011 2 35 10001100011 10000110011 2 36
11001100011 11000110011 2 37 0011100110000 0011001100000 3 38
0111100110000 0111001100000 3 39 1111100110000 1111001100000 3 40
0011100110001 0011001100001 3 41 0111100110001 0111001100001 3 42
1111100110001 1111001100001 3 43 0011100110011 0011001100011 3 44
0111100110011 0111001100011 3 45 1111100110011 1111001100011 3 46
0000110011100 0000011001100 3 47 1000110011100 1000011001100 3 48
1100110011100 1100011001100 3 49 0000110011110 0000011001110 3 50
1000110011110 1000011001110 3 51 1100110011110 1100011001110 3 52
0000110011111 0000011001111 3 53 1000110011111 1000011001111 3 54
1100110011111 1100011001111 3
[0131] (Explanation for Adaptive Control Value)
[0132] FIG. 12 is an internal block diagram of the adaptive control
value calculator 110. Several types of preset patterns (pattern 1)
are registered in a pattern determining unit 501 and a signal
indicating one of the registered patterns is output when decoded
binary data coincides with the registered pattern. In a pattern
memory 502, three types of patterns (pattern 1, pattern 2, pattern
3) registered therein are output according to the signal from the
pattern determining unit. In ideal signal calculators 511, 512,
513, passes corresponding to the PR(1,2,2,2,1) characteristic are
formed based on the output patterns. In distance calculators 521,
522, 523, passes and Euclidean distances (which are respectively
set to E1, E2, E3) between the passes and the equalized
reproduction signal are calculated. The difference between the
Euclidean distances E2 and E1 and the difference between the
Euclidean distances E3 and E1 are calculated in difference
calculators 531, 532 and stored in distance difference memories
541, 542. The locations of the distance difference memories in
which the differences are to be stored are determined depending on
the output signal of the pattern determining unit. When a preset
amount of data is recorded/reproduced, parameter calculating means
550 calculates an adaptive control value based on data stored in
the distance difference memories.
[0133] In this embodiment, the lengths of marks and spaces are
divided into three types of 2T/3T/.gtoreq.4T and an adaptive
control value is calculated for each pattern with respect to the
mark and space. The contents of the pattern 1, pattern 2, pattern 3
stored in the pattern memory are shown in the TABLE 5. First and
second columns of the TABLE 5 correspond to the adaptive control
parameters of the TABLE 2. For example, the second row of the TABLE
5 shows a pattern used to derive an adaptive control value for 2T
space/2T mark recording. The pattern 2 is obtained by changing a
portion corresponding to the code bit string "10" (or "01")
appearing in the pattern 1 to "00" (or "11"). Further, the pattern
3 is obtained by changing a portion corresponding to the code bit
string "10" (or "01") appearing in the center of the pattern 1 to
"11" (or "00").
5TABLE 5 T.sub.SFP, T.sub.SFP, T.sub.ELP for T.sub.ELP for Land
Land Track Track Pattern 2 Pattern 1 Pattern 3 Dl dg ?11011100?
?11001100? ?11000100? gl gg 110011100? 110001100? 110000100? jl jg
?00011100? ?00001100? ?00000100? el eg ?110111100 ?110011100
?110001100 hl hg 1100111100 1100011100 1100001100 kl kg ?000111100
?000011100 ?000001100 fl fg ?110111110 ?110011110 ?110001110 il ig
1100111110 1100011110 1100001110 ll lg ?00011111? ?00001111?
?00000111? ml mg ?00100011? ?00110011? ?00111011? pl pg ?00100001?
?00110001? ?00111001? sl sg ?00100000? ?00110000? ?00111000? nl ng
001100011? 001110011? 001111011? ql qg 0011000011 0011100011
0011110011 tl tg ?01100000? ?01110000? ?01111000? ol og ?11100011?
?11110011? ?11111011? rl rg ?111000011 ?111100011 ?111110011 ul ug
?11100000? ?11110000? ?11111000?
[0134] In the TABLE 5, "?" expresses a code bit "0" or "1". If "?"
in the pattern 1 is "0" ("1"), "?" in a corresponding portion of
each of the patterns 2, 3 is also "0" ("1"). For example, the
second row of the TABLE 5 is expanded as shown in the TABLE 6.
6 TABLE 6 dl dg 0110111000 0110011000 0110001000 0110111001
0110011001 0110001001 1110111000 1110011000 1110001000 1110111001
1110011001 1110001001
[0135] The basic concept of the adaptive control value calculating
operation of this invention is shown in FIGS. 13, 14A, 14B and 15.
For example, consider a case wherein the patterns 1, 2, 3 selected
by the pattern determining unit each have an arrangement of "0",
"1" as shown in the upper portion of FIG. 13. Passes calculated
based on the patterns 1, 2, 3 have waveforms shown in the lower
portion of FIG. 13. The passes of the patterns 1, 2, 3 shown in
FIG. 13 are set to P1(t), P2(t), P3(t) and a reproduction signal is
set to Y(t). Then, Euclidean distances E1, E2, E3 between P1(t),
P2(t), P3(t) and Y(t) can be expressed as follows.
E1=.SIGMA.{Y(t)-P1(t)}.sup.2
E2=.SIGMA.{Y(t)-P2(t)}.sup.2
E3=.SIGMA.{Y(t)-P3(t)}.sup.2
[0136] The condition that the result of identification indicates
the pattern E2 even when the pattern 1 is recorded is as
follows.
E1>E2
[0137] Likewise, the condition that the result of identification
indicates the pattern E3 even when the pattern 1 is recorded is as
follows.
E1>E3
[0138] In this case, consider the following relation.
D2=E2-E1
D3=E3-E1
[0139] The distributions of D2, D3 are expressed as shown in FIGS.
14A, 14B. In FIGS. 14A, 14B, a region in which the distribution
becomes equal to or smaller than "0" corresponds to an
identification error. In FIG. 14A, the pattern 2 is selected when
the distribution is equal to or less than "0". Further, in FIG.
14B, the pattern 3 is selected when the distribution is equal to or
less than "0". If the mean values of D2, D3 are respectively set to
M2, M3 and the standard deviations are respectively set to
.sigma.2, .sigma.3, a margin Mgn2 which prevents the identification
result from being set to the pattern 2 when the pattern 1 is
recorded is obtained as follows.
Mgn2=M2/.SIGMA.2
[0140] Likewise, a margin Mgn3 which prevents the identification
result from being set to the pattern 3 when the pattern 1 is
recorded is obtained as follows.
Mgn3=M2/.sigma.3
[0141] In this case, it is considered that an event in which the
identification result becomes the pattern 2 when the pattern 1 is
recorded and an event in which the identification result becomes
the pattern 3 are conflicting events. The distributions of D2 and
-D3 are shown in FIG. 15. A certain value Ec is provided on the
abscissa and margins Mgn2', Mgn3' from the distributions D2 and -D3
to Ec can be expressed as follows.
Mgn2'=(M2-Ec)/.sigma.2
Mgn3'=(M3+Ec)/.sigma.3
[0142] A solution for Ec is attained as follows when the relation
of Mgn2'=Mgn3' is set.
Ec=(.sigma.3*M2-.sigma.2*M3) (.sigma.2+.sigma.3)
[0143] This means that the probability that the identification
result becomes the pattern 2 when the pattern 1 is recorded becomes
equal to the probability that the identification result becomes the
pattern 3 if the whole distributions are shifted by Ec. This
corresponds to a case wherein an error occurs with the most
difficulty. That is, a preferable recording operation can be
performed by controlling the recording waveform corresponding to
Ec. The sign of Ec corresponds to whether the mark is made larger
or smaller and the absolute value of Ec corresponds to the
variation amount of the mark size.
[0144] The unit of Ec is a Euclidean distance. The unit of the
adaptive control parameters T.sub.SFP, T.sub.ELP is time. It is
difficult to convert the Euclidean distance to time.
[0145] Therefore, the adaptive control parameters may be adjusted
based on Ec as follows. A dead zone is set at or near "0" and the
adaptive control value is set to "0" if Ec lies in the dead zone.
If Ec is larger than the dead zone, the adaptive control value is
set to +1. On the other hand, if Ec is smaller than the dead zone,
the adaptive control value is set to -1. The adaptive control
parameters T.sub.SFP, T.sub.ELP are increased or decreased by
.DELTA.T (=T/32) according to the adaptive control value [-1, 0,
+1]. After the adaptive control parameters T.sub.SFP, T.sub.ELP are
increased or decreased by .DELTA.T, they are recorded/reproduced
again to derive adaptive control values. The above operation is
repeatedly performed until all of the adaptive control values
become "0".
[0146] In the above example, the operation is repeatedly performed
until all of the adaptive control values become "0", but this
invention is not limited to this case. For example, the operation
may be repeatedly performed until 80% or more of the adaptive
control values become "0". Alternatively, the operation may be
repeatedly performed until the adaptive control values become
approximately equal to "0". Further, the number of repetition times
is previously specified and the operation is repeatedly performed
by a specified number of times.
[0147] The adaptive control values are set to three types of [-1,
0, +1], but this is not limitative. For example, they may be set to
five types of [-2, -1, 0, +1, +2]. Further, .DELTA.T is set to
T/32, but it is not limited to this case. For example, .DELTA.T can
be set to T/16.
[0148] (Second Recording Parameter Adjusting Procedure)
[0149] The second recording parameter adjusting procedure of this
invention is explained. Since the adjusting procedure of the
recording parameter for land tracks and the adjusting procedure of
the recording parameter for groove tracks are the same, only the
recording parameter adjusting procedure for land tracks is
explained here. The outline of the adjusting procedure is shown in
FIG. 16.
[0150] (Adjusting Peak Power and Bias Power 1: Step SA1 of FIG.
16)
[0151] 1. The peak power is set to an initial value P.sub.P0.
P.sub.P0 is previously recorded in a preset position on the optical
disk. Data on the corresponding portion is reproduced and a
reproduced value is set. Likewise, the bias power 1, bias power 2,
bias power 3 are set to initial values P.sub.B10, P.sub.B20,
P.sub.B30. P.sub.B10, P.sub.B20, P.sub.B30 are previously recorded
in preset positions on the optical disk. Likewise, time-base
parameters T.sub.SFP, T.sub.EFP, T.sub.MP, T.sub.SLP, T.sub.ELP,
T.sub.LC are set to initial values. However, T.sub.SFP, T.sub.EFP
are each set to nine values shown in the TABLE 2. Likewise,
T.sub.LC is set to three values shown in the TABLE 2. The initial
value of the time-base parameter is previously recorded in a preset
position on the optical disk. In this example, the peak power and
bias power 1 are treated as variables.
[0152] 2. After random data is successively recorded ten times on a
certain track, the random data is reproduced to derive an
equalization coefficient. In the succeeding procedure, the thus
derived equalization coefficient is used.
[0153] 3. Random data is successively recorded ten times on a
certain track. The operation of successively recording random data
ten times is performed each time the peak power and bias power 1
are adjusted. PRSNR is measured each time the peak power and bias
power 1 are adjusted. The peak power and bias power 1 are adjusted
so as to increase PRSNR. The adjusting operation is performed to
set the ratio of the peak power to the bias power 1 equal to that
of P.sub.P0 to P.sub.B10.
[0154] 4. The relation between the peak power and PRSNR is derived
in the procedure 3 (refer to FIG. 4).
[0155] 5. The maximum value of PRSNR is derived.
[0156] 6. The upper limit value P.sub.POU and the lower limit value
P.sub.POL which is set to 80% or more of the maximum value of PRSNR
are derived.
[0157] 7. The adjusted value P.sub.P1 of the peak power and the
adjusted value P.sub.B11 of the bias power 1 are derived according
to the following equations.
P.sub.P1=(P.sub.POL+P.sub.POU)/2
P.sub.B11=(P.sub.B10/P.sub.P0).times.P.sub.P1
[0158] An adjusting method of setting the maximum value of PRSNR
derived in the procedure 5 to P.sub.P1 may be used. In the
procedure 6, the specified value is set to 80% or more of the
maximum value, but this is not limitative. Further, PRSNR is set as
an evaluation value, but SbER may be used as an evaluation value.
When SbER is used as the evaluation value, the peak power and bias
power 1 are adjusted to make the SbER value smaller.
[0159] (Adjusting T.sub.MP: Step SA2 of FIG. 16)
[0160] 1. The peak power is set to P.sub.P1. The bias power 1, bias
power 2, bias power 3 are set to P.sub.B11, P.sub.B20, P.sub.B30.
Time-base parameters T.sub.SFP, T.sub.EFP, T.sub.MP, T.sub.SLP,
T.sub.ELP, T.sub.LC are set to initial values. In this example,
T.sub.MP is treated as a variable.
[0161] 2. Random data is successively recorded ten times on a
certain track. The operation of successively recording random data
ten times is performed each time T.sub.MP is adjusted. PRSNR is
measured each time T.sub.MP is adjusted. T.sub.MP is adjusted so as
to increase PRSNR.
[0162] 3. The relation between T.sub.MP and PRSNR is derived in the
procedure 2 (refer to FIG. 5).
[0163] 4. The maximum value of PRSNR is derived.
[0164] 5. The upper limit value T.sub.MPU and the lower limit value
T.sub.MPL of T.sub.MP which is set to 80% or more of the maximum
value of PRSNR are derived.
[0165] 6. The adjusted value T.sub.MP(cal) of T.sub.MP is derived
as follows.
T.sub.MP(cal)=(T.sub.MPL+T.sub.MPU)/2
[0166] An adjusting method of setting the maximum value of PRSNR
derived in the procedure 4 to T.sub.MP(cal) may be used. In the
procedure 5, the specified value is set to 80% or more of the
maximum value, but this is not limitative. Further, PRSNR is set as
an evaluation value, but SbER may be used as an evaluation value.
When SbER is used as the evaluation value, T.sub.MP is adjusted to
make the SbER value smaller.
[0167] (Determination as to Whether PRSNR and SbER Satisfy
Specified Reference Value: Step SA3 of FIG. 16)
[0168] 1. The peak power is set to P.sub.P1. The bias power 1, bias
power 2, bias power 3 are set to P.sub.B11, P.sub.B20, P.sub.B30.
T.sub.MP is set to T.sub.MP(cal). The other time-base parameters
T.sub.SFP, T.sub.EFP, T.sub.SLP, T.sub.ELP, T.sub.LC are set to
initial values.
[0169] 2. Random data is successively recorded ten times on five
adjacent tracks.
[0170] 3. Data recorded on a central one of the tracks used in the
procedure 2 is reproduced and an equalization coefficient is
derived. The thus derived equalization coefficient is used in the
succeeding procedure.
[0171] 4. PRSNR and SbER are measured.
[0172] 5. If PRSNR is set equal to or more than 15.0 and SbER is
set equal to or less than 5.times.10.sup.-5, the recording
parameters set in the procedure 1 are used as parameters obtained
after adjustment and then the recording parameter adjusting
procedure is terminated. If PRSNR is less than 15.0 or SbER is
larger than 5.times.10.sup.-5, the following adaptive control
parameter adjusting procedure is performed.
[0173] In the procedure 5, PRSNR is set equal to or more than 15.0
and SbER is set equal to or less than 5.times.10.sup.-5, but this
invention is not limited to this case. For example, PRSNR may be
set equal to or more than 13.0 and SbER may be set equal to or less
than 5.times.10.sup.-4.
[0174] (Adjustment of Adaptive Control Parameters T.sub.SFP,
T.sub.ELP: Step SA4 in FIG. 16)
[0175] 1. The peak power is set to P.sub.P1. The bias power 1, bias
power 2 and bias power 3 are set to initial values P.sub.B11,
P.sub.B20 and P.sub.B30. T.sub.MP is set to T.sub.MP(cal). The
other time-base parameters T.sub.SFP, T.sub.EFP, T.sub.SLP,
T.sub.ELP, T.sub.LC are set to initial values. In this example,
nine types of T.sub.SFP, T.sub.EFP, that is, dl, el, fl, gl, hl, il
jl, kl, ll, ml, nl, ol, pl, q1, rl, sl, tl, ul shown in the TABLE 2
are independently adjusted.
[0176] 2. Random data of the length equal to or larger than 928512
channel bits is successively recorded ten times on a certain track.
The operation of successively recording random data ten times is
performed each time T.sub.SFP, T.sub.ELP are adjusted.
[0177] 3. The adaptive control value is measured. The adaptive
control value is calculated for each of nine types of T.sub.SFP,
T.sub.ELP and the value is set to +1, 0 or -1.
[0178] 4. If the adaptive control value for certain T.sub.SFP
(T.sub.ELP) is +1, T.sub.SFP (T.sub.ELP) is reduced (increased) by
time .DELTA.T. If the adaptive control value for certain T.sub.SFP
(T.sub.ELP) is -1, T.sub.SFP (T.sub.ELP) is increased (reduced) by
time .DELTA.T. In this case, .DELTA.T is T/32.
[0179] 5. The procedures 2 to 4 are repeatedly performed until all
of the adaptive control values are set to 0. If all of the adaptive
control values are set to 0, T.sub.SFP and T.sub.ELP obtained at
this time are respectively set to T.sub.SFP(cal) and
T.sub.ELP(cal).
[0180] In the above example, the operation is repeatedly performed
until all of the adaptive control values become "0", but this
invention is not limited to this case. For example, the operation
may be repeatedly performed until 80% or more of the adaptive
control values become "0". Alternatively, the operation may be
repeatedly performed until the adaptive control values become
approximately equal to "0". Further, the number of repetition times
is previously specified and the operation may be repeatedly
performed by a specified number of times.
[0181] The adaptive control values are set to three types of [-1,
0, +1], but this is not limitative. For example, they may be set to
five types of [-2, -1, 0, +1, +2]. Further, .DELTA.T is set to
T/32, but it is not limited to this case. For example, .DELTA.T can
be set to T/16.
[0182] (Determination as to Whether Optical Disk is Improper or
Not: Step SA5 in FIG. 16)
[0183] 1. The peak power is set to P.sub.P1. The bias power 1, bias
power 2 and bias power 3 are set to initial values P.sub.B11,
P.sub.B20 and P.sub.B30. T.sub.MP, T.sub.SFP, T.sub.ELP are
respectively set to T.sub.MP(cal), T.sub.SFP(cal), T.sub.ELP(cal).
The other time-base parameters T.sub.EFP, T.sub.ELP, T.sub.LC are
set to initial values.
[0184] 2. Random data is successively recorded ten times on five
adjacent tracks.
[0185] 3. Data recorded on a central one of the tracks used in the
procedure 2 is reproduced and an equalization coefficient is
derived. In the succeeding procedure, the thus derived equalization
coefficient is used.
[0186] 4. PRSNR and SbER are measured.
[0187] 5. If PRSNR is set equal to or more than 15.0 and SbER is
set equal to or less than 5.times.10.sup.-5, the recording
parameters set in the procedure 1 are used as parameters obtained
after adjustment and then the recording parameter adjusting
procedure is terminated. If PRSNR is less than 15.0 or SbER is
larger than 5.times.10.sup.-5, the optical disk is determined as an
improper optical disk and discharged.
[0188] In the procedure 5, PRSNR is set equal to or more than 15.0
and SbER is set equal to or less than 5.times.10.sup.-5, but this
invention is not limited to this case. For example, PRSNR may be
set equal to or more than 13.0 and SbER may be set equal to or less
than 5.times.10.sup.-4.
[0189] (Rectangular Recording Waveform)
[0190] In the first and second inventions, a so-called multi-pulse
waveform is used as a recording waveform. However, this invention
is not limited to this case and a rectangular waveform such as a
recording waveform ("b" in FIG. 17) may be used. "a" in FIG. 17
indicates recording binary data. In this case, the recording
parameters are shown in the TABLE 7.
7 TABLE 7 Recording Parameter Peak Power, Bias Power 1, for Land
Track Bias Power 2, T.sub.SFP, T.sub.ELP, T.sub.LC Recording
Parameter Peak Power, Bias Power 1, for Groove Track Bias Power 2,
T.sub.SFP, T.sub.ELP, T.sub.LC
[0191] The recording parameter adjusting procedure used when the
rectangular wave is used as the recording wave is shown in FIG. 18
or 19.
[0192] A waveform shown in FIG. 20 obtained by modifying the
rectangular recording waveform can be used as the recording
waveform "b". "a" in FIG. 20 is recording binary data. The
recording wave to which this invention can be applied is not
limited to the above case.
[0193] In the above embodiments, a so-called land & groove
recording type optical disk is used. However, this invention is not
limited to this case and an optical disk in which information is
recorded only on the land or groove can be used.
[0194] In the above embodiments, the mark length and space length
are classified into three groups of 2T, 3T and .gtoreq.4T, but this
invention is not limited to this case. For example, the mark length
and space length can be classified into four groups of 2T, 3T, 4T
and .gtoreq.5T.
[0195] In the above embodiments, PR(1,2,2,2,1) is used, but this
invention is not limited to this case. For example, this invention
can be applied to another PR class, for example, PR(1,2,2,1) or
PR(3,4,4,3).
[0196] In the above embodiments, a case wherein the minimum run
length is "1" is explained, but this invention is not limited to
this case. For example, this invention can be applied to a case
wherein the minimum run length is "2".
[0197] As described above, in the optical disk system using the
PRML identification system, optimum recording parameters can be
derived by the optical disk recording/reproducing method of this
invention. Further, in the optical disk system using the PRML
identification system, the recording parameter can be derived in a
short period of time by use of the optical disk
recording/reproducing method of this invention. An optical disk
recording/reproducing apparatus which can correctly
record/reproduce information can be provided by using a recording
wave derived by use of the optical disk recording/reproducing
method of this invention. Further, it is possible to provide an
optical disk on which information is correctly recorded by
recording information by use of a recording wave derived according
to the optical disk recording/reproducing method of this
invention.
[0198] This invention is not limited to the above embodiments and
can be variously modified without departing from the technical
scope thereof at the embodying stage. Further, various inventions
can be made by adequately combining a plurality of constituents
disclosed in the above embodiments. For example, some constituents
can be omitted from the whole constituents shown in the above
embodiments. In addition, constituents over the different
embodiments can be adequately combined.
[0199] Additional advantages and modifications will readily occur
to those skilled in the art. Therefore, the invention in its
broader aspects is not limited to the specific details and
representative embodiments shown and described herein. Accordingly,
various modifications may be made without departing from the spirit
or scope of the general inventive concept as defined by the
appended claims and their equivalents.
* * * * *